Corrosion of Tantalum and Niobium and their Alloys

Corrosion behavior of construction materials for ionic liquid hydrogen compressor

“…In addition, 0.8 wt. % of niobium and tantalum in the structure of AISI 347, and its role in the formation of oxide layer can explain the high corrosion resistance of AISI 347 [36]. The lowest corrosion resistance of AISI 321 indicated that molybdenum, tantalum, and niobium played more important roles in increasing the corrosion resistance of the alloys than titanium.…”

“…%) in all the ionic liquids tested (Figure 3-7 of all the alloys in all the electrolytes tested. This could be due to a lack of niobium and tantalum in the structure of Hastelloy ® C-276 (comparison with Inconel ® 625), since small amounts of niobium and tantalum could increase the stability of the passivation layer [36,37].…”

The effect of sodium hydroxide on niobium carbide precipitates in thermally sensitised 20Cr-25Ni-Nb austenitic stainless steel

“…Despite being more reactive than interstitial carbides, Warren [31] reported no reaction of transition metal carbides (TiC, ZrC and SiC) with boiling pH 14.6 NaOH. A book of metal etchants [32], indicated that the NbC system may be slowly etched by use of hot H2SO4, (despite elemental Nb being passive in this environment [21]). Alternatively etching by use of HF was recommended, which slowly etches the material.…”

“…Therefore, the observed behaviour might suggest that the characteristics of these Nb-rich precipitates reflect the behaviour of metallic Nb rather than the carbide. Lyon discussed the corrosion of Nb and its alloys in [21], with only little literature on the electrochemistry of Nb other than in extreme environments, Lyon concluded that the element is possibly passive in most environments. Elemental Nb spontaneously forms a very stable passive oxide film (Nb2O5) allowing it to passivate in almost all environments at standard temperature and pressure, giving exceptional corrosion resistance.…”

Atomic layer deposition: state-of-the-art and research/industrial perspectives

“…Taking into account their nanometric thickness and their chemical composition, ALD oxide coatings may be considered an artifi cial imitation of spontaneously formed oxide layers that can be found on the surface of different metals and metallic alloys and in particular titanium and tantalum, well known for their excellent corrosion protection in most aggressive media, owing to their conformity, the absence of defects and the wide ranges of chemical and thermal stability in most common environments (Lyon, 2010;Shoesmith & No ë l, 2010). Those ceramic layers have in fact the property of insulating the more reactive substrate and protect it from aggressive media, reducing corrosion.…”